In many clinical situations, blood vessels are occluded for a variety of purposes, such as to control bleeding, to prevent blood supply to tumors, to block blood flow within an aneurysm, or for prophylactic purposes, such as prophylactic gastroduodenal embolization or prophylactic hypogastric embolization. Vaso-occlusive devices are surgical implants placed within blood vessels or vascular cavities, typically by the use of a catheter, to form an occlusion at the site. Some vaso-occlusive devices may be inflated with materials that harden into solid masses, while other vaso-occlusive devices may have thrombogenic properties and cause a thrombus to form. The properties of the vaso-occlusive devices may cause a blockage of blood flow past the vaso-occlusive devices or into cavities where the vaso-occlusive devices were placed.